The present invention relates to a driver assist system. More specifically, the present invention relates to a real time accessible geospatial database that can be used with driver assist subsystems.
Geographic information systems (GIS) are systems that are used to store and manipulate geographic data. GIS is primarily used for collection, analysis, and presentation of information describing the physical and logical properties of the geographic world. A system referred to as GIS-T is a subset of GIS that focuses primarily on the transportation aspects of the geographic world. There have been many products developed that provide drivers with route and navigation information. Some automobile manufacturers provide onboard navigation systems.
However, these systems are based on conventionally designed and commonly used digital maps that are navigatable road network databases, covering various geographic regions. Such maps are designed for turn-by-turn, and door-by-door route guidance which can be used in conjunction with a global positioning system (GPS) unit and a display for providing route assistance to a driver.
Such conventionally designed digital maps usually refer to digital road networks that are typically set up to do routing, geocoding, and addressing. In a road network, every intersection in a map is a node and the links are the roads connecting the nodes. There are also intermediate nodes that define link (road) geometry. These systems tend to employ a linear referencing system—that is, the location of nodes are defined relative to other nodes, and intermediate attributes are defined relative to a distance from a node (e.g., the speed limit sign is 5 miles along this specified road/link starting from this specified intersection/node).
Some existing maps have been adapted to assist onboard “intelligent” vehicle systems. For example, an autonomous van with computer controlled steering, throttle, brakes and direction indicators has been developed. The lateral guidance for the van was aided by knowledge of road curvatures stored in a digital road map database. Cameras were positioned to look at various angles away from the van. The road geometry was used to determine which camera would have the best view of the road for driving.
Another autonomous vehicle control was augmented with a digital map as well. In that instance, video cameras, ultrasonic sensors and a three-dimensional scanning laser range finder were used along with a differential GPS system to control and navigate an autonomous vehicle. A three-dimensional map was used to compensate for the inaccuracies of the DGPS system.
Similarly, digital road map databases have been used to help in collision avoidance. The map databases were used to detect when the vehicle was approaching an intersection and to provide the angles of adjoining roadways to aim radar.
Similarly, a digital railway map has been used in the field of positive train control. The map was similar to a road network database and was used to calculate braking distances and make enforcement decisions for automatic brake control of a train.
All of the above-described systems discuss the use of conventionally designed digital road maps to augment the workings of onboard vehicle systems. However, they are limited to the simple road map information in conventional digital maps, augmented with a small amount of additional information.
Existing digital road network databases, although becoming more prevalent, simply do not have adequate resolution, accuracy or access times for intelligent vehicle applications developed for real time driver assistant technologies. For example, in European and Japanese urban areas, map scales for route guidance and map matching may need to be 1:10,000, while in rural areas, the map scales may only need to be 1:50,000. The urban areas require a higher resolution since the infrastructure density is greater.
However, the map scale needed for a real time driver assist system approaches 1:1—that is, what is in the database must substantially exactly correspond to what is in the real world.